Diabetes MellitusManual of Clinical Nutrition Management III- 23 Copyright © 2013 Compass Group, Inc.
DIABETES MELLITUS: CONSIDERATIONS FOR EXERCISE
Discussion
It is becoming increasingly clear that exercise may be a therapeutic tool in a variety of patients with, or at risk
for diabetes (1). Before beginning an exercise program, the individual with diabetes should undergo a detailed
medical evaluation with appropriate diagnostic studies (1). Some types of activities may be contraindicated
for people with hypertension, retinopathy, neuropathy, foot ulcers, and other complications of diabetes
mellitus. A detailed discussion of issues related to each type of complication is presented in reference 1. For
individuals with type 2 diabetes, exercise in the amount of 90 to 150 minutes a week (both aerobic and
resistance/strength training) reduces A1C, improves insulin sensitivity, decreases dyslipidemia, and
decreases blood pressure (Grade I)* (2,3). Regular physicial activity also has shown to help persons with type 2
diabetes achieve and maintain weight loss goals (2,3). Physical activity provides a way to create an energy
deficit which can facilitate and maintain weight loss. Research has shown the combination of diet, exercise,
and behavior modification to be the most effective method for reaching and maintaining weight loss goals
(1,2,3).
Alteration in Energy and Nutrient Requirements
For individuals wishing to maintain their weight, increases in activity require increases in caloric intake. For
adult men engaging in light activities, 30 kcal/kg body weight may suffice, while those who engage in heavy
activity may need 50 kcal/kg. For women, light activity may increase need to 30 kcal/kg, while heavy activity
may elevate needs to 44 kcal/kg (4). Protein needs may be increased with physical activities to a level of 1.2
grams protein/kg body weight for both men and women (4). Fluid replacement is also an important
consideration (4).
Prevention of Exercise Induced Hypoglycemia
Type 1 Diabetes: Because physical activity may vary considerably from day to day, adjustments in energy
intake and insulin dosage may be required to avoid hypoglycemia in individuals with type 1 diabetes. Several
strategies may be used to avert hypoglycemia during or after exercise. When exercise is planned, insulin dose
should be adjusted to prevent hypoglycemia (1,2). If exercise is not planned, additional carbohydrate may
need to be consumed (1,2). Carbohydrate supplementation is based on the blood glucose level before exercise,
previous experience with the particular form of exercise, and the individual’s insulin regimen (1,2). Moderate
intensity exercise increases glucose uptake by 2-3 mg/kg/min above usual requirements. Thus, a 70 kg
person would need 8.4 to 12.6 [10 to 15] g of carbohydrate per hour of moderate physical activity (2). More
carbohydrate may be needed for higher intensity activities or prolonged exercise (eg, > 60 minutes) (1,2). An
individual may be at risk for hypoglycemia up to 24 hours after the exercise bout (1,2). Individuals who prefer
to consume carbohydrates to prevent hypoglycemia during exercise should test their blood glucose prior to
exercising, and consume an amount of food (15 grams carbohydrate) which will prevent hypoglycemia but
not cause hyperglycemia (2). The following general guidelines can be helpful in regulating the glycemic
response to exercise in type 1 diabetes (1):
Avoid exercise if fasting glucose levels are > 250 mg/dL and ketosis is present, and use caution if glucose
levels are > 300 mg/dL and no ketosis is present
Ingest added carbohydrate if pre-exercise glucose levels are < 100 mg/dL
Type 2 Diabetes: Supplemental food before and during exercise is not needed to prevent hypoglycemia and
is not recommended, except under conditions of strenuous, prolonged exercise, such as endurance sports (2).
For individuals taking sulfonylureas, there is a slightly increased risk of hypoglycemia during exercise, and
supplemental energy intake may be required in some cases (2). The need may be determined by glucose self-
monitoring. Individuals with type 2 diabetes who use insulin should also monitor their blood glucose levels
closely during and after exercise. Several strategies may be used to avert hypoglycemia during or after
vigorous, prolonged, or nonhabitual exercise. These involve the consumption of supplemental carbohydrate-
containing foods before, during, and after exercise, as well as adjustment of insulin dosage and timing (1,2).
*The Academy of Nutrition and Dietetics has assigned grades, ranging from Grade I (good/strong) to Grade V (insufficient evidence), to
evidence and conclusion statements. The grading system is described in Section III: Clinical Nutrition Management A Reference Guide,
page III-1.
References
- Physical activity recommendations. In: Standards of medical care in diabetes-2013. Diabetes Care. 2013;36(suppl 1):24S-25S..
- American Diabetes Association. Nutrition recommendations and interventions for diabetes. Diabetes Care. 2008;31 (suppl 1): 61S-
78S.